Bucket positioning device



July 7, 1970 c. R. JEFFERSON ET AL 3,

BUCKET POSITIONING DEVICE Filed Oct. 25, 1968 RESERVOIR INVENTORS fulfi m CHARLES R.JEFFERSON 7 48 49 ALLAN L. FREEDY BY wi 7 r4 7 ATTORNEYS United States Patent 3,519,155 BUCKET POSITIONING DEVICE Charles R. Jefferson, Pekin, and Allan L. Freedy, Aurora, 111., assignors to Caterpillar Tractor Co., Peoria, Ill., a corporation of California Filed Oct. 25, 1968, Ser. No. 770,670 Int. Cl. E02f 3/28 U.S. Cl. 214-764 4 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to a positioning device for bucket loaders and more particularly to an electrical switch and actuating means arranged upon relatively extendible portions of the tilt motor to terminate operation of the tilt motor as the bucket is moved toward a preferred position by the tilt motor.

Bucket loaders generally have the bucket pivotably supported by lift arms with tilt jacks interconnected between the lift arms and the bucket by suitable tilt linkage. The tilt linkage generally maintains the bucket in a constant tilt position while it is being raised or lowered upon the lift arm. Additionally, the tilt linkage permits the bucket to be pivoted forwardly or rearwardly, for example, between its carry and dump position, in response to operation of the tilt jacks.

It has been found desirable to provide means for automatically positioning the bucket to perform certain func: tions. Automatic positioning means are most commonly employed for establishing the bucket in a load position where its floor is generally parallel to the ground. The pivoted position of the bucket is somewhat more critical in this position and the operators view of the bucket is generally obstructed as the bucket is approaching ground level.

The load position of the bucket can be best determined by relative extension of the hydraulic tilt jack. In the prior art, hydraulic control valves have been commonly employed for establishing this position of the bucket. However, the valve components are generally exposed to dirt and other debris during loading so that they are subject to fouling or mechanical damage. Such failure commonly prevents effective operation of the bucket positioning arrangement and sometimes interfere with operation of the entire tilt control system.

In view of these problems, it is an object of the present invention to provide an electrical bucket positioning arrangement which is positively responsive to the position of the bucket and which is generally not subject to failure. An additional advantage for the present invention lies in the fact that it eliminates the use of long hydraulic lines communicating a bucket positioning valve with the tilt control system. Accordingly, the present invention avoids the possibility of damage and leakage within such hydraulic lines which might prevent effective operation of the tilt control system.

Since bucket loaders of the type presently contemplated normally employ detented tilt control valves, it is, also an object of the invention to provide means for momentarily rendering the detent mechanism inoperative as the bucket is racked back from its load position. This See feature facilitates operator control over the bucket during loading in a manner described in greater detail below.

Other objects and advantages of the present invention are made apparent in the following description having reference to the accompanying drawing.

The accompanying drawing illustrates the forward portion of a bucket loader and includes an exploded view, with parts in section, of a tilt control system.

Having reference to the drawing, a bucket loader vehicle 11 has a bucket 12 pivotably supported at 13 upon a pair of lift arms, one of which is indicated at 14. A tilt jack having a cylinder 16 and extendible rod 17 is interconnected between each of the lift arms 14 and the bucket 12 by means of tilt linkage which includes a pair of levers 18, 19 and a link 21 connecting the forward tilt linkage lever 19 with the bucket 12.

A tilt control system for operating the tilt jack 16 is illustrated by the exploded portion of the drawing indi-- cated at 22. A tilt control valve 23 comprises a housing 24 defining a bore 26 which is in communication with a fluid pump 27 and the head and rod end of the tilt cylinder 16 by means of conduits 28, 29 and 31 respectively. A spool 32 is reciprocably disposed in the valve bore 26 for regulating fluid flow from the pump conduit 28 to the hydraulic tilt jack 16. A centering spring 33 within the housing 24 tends to move the spool 32 into a closed position as shown in the drawing to prevent or terminate operation of the tilt jack 16. The spool 32 is connected to a control lever 34 and handle 36. The control lever 34 is shown in a hold position indicated at H which corresponds to the spring centered position of the spool 32 as shown in the drawing.

The bucket 12, which is shown in its load position, may be racked back to a carry position by counter-clockwise rotation of the control lever 34 into the position indicated at R. With the control lever in this position, the spool 32 is shifted leftwardly to communicate fluid from the pump conduit 28 to the rod end of the tilt jack 16 and to cause retraction of the jack 16. To tilt the bucket forwardly past its load position shown in the drawing to a position suitable for dumping material from the bucket, the control lever 34 is rotated clockwise to a dump position indicated at D. The spool 32 is accordingly shifted rightwardly and communicates the pump conduit 28 with the head end of the tilt jack 16 through the conduit 29.

To permit detent latching of the control valve in either its rack back or dump positions, the end of the control lever 34 opposite its connection with the spool 32 defines detent notches 37 and 38. A roller 39 is supported by an arm 41 which is urged leftwardly by a spring 42. As the control lever 34 is rotated in either direction, the roller 39 rides into one of the detent notches 37 and 38 and prevents the control lever and spool from returning to a centered position under the influence of the spring 33. The operator may manually override the detent arrangement to reposition the control spool 32 regardless of the position of the bucket 12.

The present invention provides an electrical switch 43 and actuating means 44 which are respectively associated with relatively extendible portions of the tilt motor for disengaging the detent mechanism and permitting the spool 32 to assume its spring centered position. In the embodiment illustrated by the drawing, the switch and actuating means are effective to interrupt operation of the tilt motor as the bucket approaches its load position shown in the drawing.

To accomplish this function, the switch 43 is connected in series with an electrical solenoid 46 which is effective upon actuation of the switch to disengage the detent roller 39 from the control lever 34. The switch '43 is also in series with a battery 47, a normally open pressure switch 48, and a master switch 49 which controls the complete electrical circuit for the loader vehicle 11. The switch 48 remains closed during operation of the vehicle 11 but automatically functions to break the circuit with the solenoid 46 in the event the machine 11 is shut down while the switch '43 is in a closed position.

The solenoid 46 could operate directly against the detent arm 41 within the scope of the present invention. However, to minimize the cost of the electrical circuit and particularly to permit use of a smaller solenoid, the solenoid 46 is arranged to operate a valve 51. The valve 51 regulates fluid flow from the pump 27 through a conduit 52 to a hydraulically responsive slave cylinder 53 having a reciprocable spool 54 connected to the detent arm 41.

Normally, the position of the solenoid valve 51 is controlled by a spring 56 with the valve 51 positioned to block fluid communication through the conduit 52. However, upon actuation of the switch 43, the solenoid 46 is energized and shifts the valve 51 to the position shown in the drawing so that it directs fluid under pressure from the pump 27 to the slave cylinder 53. When the detent roller 39 engages either of the detent notches 37 or 38, the arm 41 and the spool 54 are shifted leftwardly from the position shown in the drawing. Since an orifice 57 restricts fluid flow from the slave cylinder to drain through a conduit 58, fluid under pressure enters the left end of the slave cylinder 53 through an internal passage 59 in the spool '54. The spool is accordingly shifted rightwardly to release the detent roller from the control lever 34 so that the control lever 34 and spool 32 are returned to their hold position by the centering spring 33.

When the bucket is shifted from its illustrated position to deactuate the switch 43, the valve 51 again assumes a closed position under the influence of the spring 56. Fluid pressure in the slave cylinder passes to drain through the line 58 so that detent engagement between the roller 39 and the control lever 34 may be reestablished by the spring 42 as the bucket again approaches its load position.

To simplify the electrical bucket positioning circuit and prevent it from being fouled by dirt or debris during loading, the switch 43 is preferably of a proximity type while the actuating mean 44 is a magnet which is effective to close the switch 43 as it comes into alignment with the switch 43.

The magnet 44 is preferably elongated as shown in the drawing so that it remains in actuating engagement with the switch 43 while the bucket is being racked back from its illustrated load position. The utility of this feature is best set forth by describing a portion of the operating cycle for the loader. When the bucket is loaded, it is racked back to its carry position and raised on the lift arms 14 to a suitable dump height. The tilt jack 16 is then extended to rotate the bucket in a clockwise direction (as viewed in the drawing) into its dump position with the front of the bucket sloping downwardly.

After the bucket load is dumped, the bucket is again lowered by the lift arm and the control lever 34 is shifted to its rack back position R. As the bucket moves counterclockwise toward the load position shown in the drawing, the magnet 44 comes into alignment with the switch 43 and energizes the solenoid 46 in the manner described above. The control lever 34 is accordingly permitted to return the spool 32 to the closed position shown in the drawing. With the bucket in the position shown, the loader vehicle 11 is then driven forwardly to urge the bucket into dirt or other material which is to be loaded.

4 It is then common practice to alternately raise and rack back the bucket by intermittently operating the tilt controls and lift controls (not shown) in order to obtain a full load in the bucket. This technique is sometimes referred to as fish-tailing.

To facilitate operation of the tilt control by the operator during this procedure, the length of magnet 44 is selected so that it remains in actuating relation with the switch 43 and renders the detent mechanism inoperable while the bucket is being racked back during this loading procedure. In this manner, the operator may freely shift the control lever 34 without having to exert force necessary to overcome the spring 42.

What is claimed is:

1. In a loader having a bucket pivotably supported on a lift frame and a hydraulic motor for pivoting the bucket, a hydraulic valve associated with the tilt motor and tending to assume a Hold position for preventing operation of the tilt motor, detent means tending to maintain the valve in a condition for operating the tilt motor and a. proximity electrical switch and actuating magnet associated respectively with telescoping portions of the motor, the detent means being responsively associated with the switch for releasing the valve from its operative condition when the bucket is pivoted to a preferred position by the tilt jack the switch and magnet being suitably positioned relative to the tilt motor for actuating the switch as the bucket is racked back toward its loading position, the magnet being of selected elongation for maintaining the switch in an actuated condition during continued rack back of the bucket to facilitate loading.

2. The invention of claim 1 wherein the tilt motor comprises a cylinder and extendible rod, the switch being mounted on a member secured to the cylinder and the magnet being adjustably secured to the rod.

3. The invention of claim 1 further comprising a hydraulically responsive slave cylinder for causing the detent means to release the valve, electrical solenoid means being associated with the slave cylinder and responsive to the switch for controlling hydraulic fluid flow to the slave cylinder.

4. A loader comprising a bucket pivotally supported on at least one lift arm, at least one hydraulic motor having a cylinder and extendible rod interconnected between the lift arm and bucket by suitably tilt linkage, a tilt control valve associated with the tilt motor and having a spring closed condition, detent means for latching the control valve in open positions for respectively racking the bucket back toward a carry position or tilting the bucket forwardly toward a dump position, electrical solenoid means associated with the detent means and operable to cause the detent means to release the control valve for return to its closed condition and a proximity switch and actuating magnet separately associated, with the tilt cylinder and rod for actuation of the switch during rack back of the bucket toward a load position intermediate its carry and dump positions, the solenoid means being responsive to actuation of the switch, the magnet being of a length suitable for maintaining the detent means in 9. released condition during continued rack back of the bucket from its load position and facilitating loading of the bucket.

References Cited UNITED STATES PATENTS 3,432,057 3/1969 Goth 214-764 HUGO 0. SCHULZ, Primary Examiner 

